How is it different from the GUI tool pack provided by MySQL?
Another freeware option that works well is MySQL Manager (lite version is free)
Toad for Oracle has been around for a long time and many people are experienced with it enough that they would just rather use Toad with DBs other than Oracle, so they don't have to learn a new tool. So their main target audience is 1) Toad for Oracle users that need to work with MySQL, 2) People that have heard good things about Toad for Oracle, haven't had a previous need to learn and SQL tool and now need to work with MySQL and 3) Those who need a broader tool than those provided with the DB. For example integration with source/version control, or having both DBA and development tools in one tool.